NBC News received a helping hand from one its competitors this week after President Trump accused the network of delivering “fake” news: Jake Tapper.

Back-and-forth between Mr. Trump and NBC over reports that he wanted a “tenfold increase” in the U.S. nuclear arsenal raised constitutional red flags with Mr. Tapper on Wednesday. The situation was pressing enough to the CNN host that he used the document as a prop during “The Lead.”

“President Trump saying today, quote, ‘It’s frankly disgusting the way the press is able to write whatever they want to write — and people should look into it,’ ” Mr. Tapper said while walking toward the camera. “Well, I have looked into it, and you might want to start looking into it, too, Mr. President.”

Mr. Tapper then held a copy of the U.S. Constitution inches away from the camera for dramatic effect.

The challenge came just hours after the president said that “people should look into” NBC’s reporting.

“I never discussed increasing it. I wanted it in perfect shape. That was just fake news by NBC, which gives a lot of fake news lately,” Mr. Trump told reporters during a press conference. “I want them in perfect condition, perfect shape. That’s the only thing I’ve ever discussed. […] It’s frankly disgusting the way the press is able to write whatever they want to write, and people should look into it.”

Fake @NBCNews made up a story that I wanted a “tenfold” increase in our U.S. nuclear arsenal. Pure fiction, made up to demean. NBC = CNN!

“Fake @NBCNews made up a story that I wanted a ‘tenfold’ increase in our U.S. nuclear arsenal,” Mr. Trump also tweeted. “Pure fiction, made up to demean. NBC = CNN! With all of the Fake News coming out of NBC and the Networks, at what point is it appropriate to challenge their License? Bad for country!”

NBC claims the president’s request was made during a “tense” July 20 meeting, which culminated with Secretary of State Rex W. Tillerson calling him a “moron.”

Trump says it’s “disgusting” that the press can write whatever they want & people should look into it. So we did. And you should too. pic.twitter.com/Bat9gjZ6R2